Do not try to --upgrade when testing bob.buildout

gitlab/before_test.sh

@@ -18,7 +18,7 @@ fi
 
 if [ "${CI_PROJECT_NAME}" == "bob.buildout" ]; then
   # zc.buildout requires special handling
-  run_cmd ${use_pip} install --upgrade --pre dist/*.whl
+  run_cmd ${use_pip} install --pre dist/*.whl
 else
   run_cmd ${use_pip} install --upgrade --use-wheel --no-index --pre dist/*.whl
 fi